In view of the large volumes of magnetic materials employed in the development of uniform magnetic fields, and the high cost of such magnetic materials, it is desirable to provide magnetic structures that have improved efficiency.
Magnetic structure designs for this purpose have been described, for example, in my copending U.S. patent application Ser. No. 424,162 filed Oct. 19, 1989, Abele, assigned to the applicant of the present application, and in my publication "Optimum Design of Two-Dimensional Permanent Magnets", T.R.-21, NYU Medical Center, NYU School of Medicine, Oct. 15, 1989, and I incorporate both of these disclosures herein by reference.
I refer to U.S. Pat. No. 4,647,887, herein for comparative purposes, in order that the differences in theory and operation of my invention, and the cladding arrangement of this citation can be more clearly appreciated.
I also refer herein to U S. Pat. No. 4,679,022, Miyamoto et al, as an example of a system employing shaping poles of known type, similar to those described with reference to FIG. 11, in order to enable a clearer appreciation of the differences between my invention and magnetic systems employing shaping poles.